1. Field of the Invention
This invention relates to a work platform and guardrail assembly for use when working on an elevated surface.
In general, when work is required on an elevated work surface such as the roof of a rail car, access to the roof is gained by means of an elevated platform. The safety laws in most jurisdictions stipulate a worker on an elevated surface with unprotected sides or edges must be protected from falling by guard rails, safety nets or a personal fall arrester.
2. Discussions of the Prior Art
Existing guardrail apparatuses for meeting these needs tend to be somewhat complicated, and consequently expensive to produce or lacking in versatility, i.e. mobility. In this connection, reference is made to U.S. Pat. Nos. 4,679,657 and 5,392,878 which issued to Ronald W. Bennett et al on Jul. 14, 1987 and Feb. 28, 1995, respectively. Both of the Bennett et al patents disclose platform structures for use on elevated surfaces (the tops of tanker trucks) which are massive and fixed in one position. In one case, a railing structure or fence for use on the top of tanks is swung between retracted and extended or use positions by means of a winch system. In the other case, a fence assembly is slid between the retracted and extended positions using rollers and fluid actuated cylinders. In both cases, the structures are bulky and utilize fixed frameworks, which require movement of the vehicle into close proximity to the structures.
Another apparatus which can be used for work on elevated work surfaces is described in U.S. Pat. No. 4,518,059, which issued to Paul Frey-Wigger on May 21, 1985. The Frey-Wigger apparatus includes a collapsible platform mounted on the free end of the boom of a crane. However, the platform of the Frey-Wigger apparatus is relatively small, and thus it is necessary to move the entire platform often when working on a large work surface such as the top of a railcar.